KR102114784B1 - Microspheres - Google Patents

Abstract

The present invention relates to a thermally expandable thermoplastic microsphere comprising a polymer shell made from an ethylenically unsaturated monomer encapsulated with a propellant, wherein the ethylenically unsaturated monomer comprises 21% to 80% by weight of methacrylamide and 20% of methacrylonitrile. It contains 70% by weight to 70% by weight, the total amount of the methacrylamide and the methacrylonitrile is 70% to 100% by weight of the ethylenically unsaturated monomer. Moreover, the present invention relates to the production and use of such microspheres.

Description

Microspheres {MICROSPHERES}

The present invention relates to a thermally expandable thermoplastic microsphere, its manufacture and use.

Expandable thermoplastic microspheres comprising a thermoplastic polymer shell encapsulated with a propellant are sold under the trade name EXPANCEL ^® and are used as blowing agents in many different applications.

In these microspheres, the propellant is usually a liquid having a boiling point higher than the softening temperature of the thermoplastic polymer shell. Upon heating, the propellant evaporates, causing the shell to soften and at the same time increase the internal pressure, causing the microspheres to expand significantly. The temperature at which expansion begins is called T _start , and the temperature at which maximum expansion is reached is called T _max . Expandable microspheres are sold in various forms, such as dry free flowing particles, aqueous slurries or partially dehydrated wet-cakes.

Expandable microspheres can be prepared by polymerizing ethylenically unsaturated monomers in the presence of a propellant. Usually, the monomer mainly includes a monomer having one carbon-carbon double bond together with a small amount of a crosslinking monomer having two or more carbon-carbon double bonds. Detailed descriptions of the various expandable microspheres and their preparation can be found, for example, in U.S. Pat. EP 486080, EP 1230975, EP 1288272, EP 1598405, EP 1811007 and EP 1964903, WO 2002/096635, WO 2004/072160, WO 2007/091960, WO 2007/091961 and WO 2007/142593, and JP Publication No. 1987-286534 And 2005-272633.

One major use of expandable microspheres is, for example, as a blowing agent for processing polymeric materials in injection molding and extrusion molding. In some cases, for example, when microspheres are processed with a polymer at high temperature for a long period of time, microspheres having high thermal stability after expansion and high thermal stability are preferred. Also preferably, the microspheres can be used at various temperatures without reforming the microsphere composition during processing using microspheres with a wide range of expansion. This will allow the end user of the microspheres to be more free in designing process conditions when optimizing foaming of a given material.

EP 1508604, EP 1577359 and EP 1964903 disclose microspheres with high expansion temperatures, which are prepared by including a significant amount of methacrylic acid monomer in a polymer shell.

Although microspheres with high expansion temperatures can be obtained, methacrylic acid monomers still complicate the manufacturing process. For example, methacrylic acid is excellent in water solubility, and manufacturing conditions require a low pH, a large amount of salt in the aqueous phase, and a water-soluble inhibitor to prevent agglomerates and clumps in the polymerization slurry. Low pH and salt can cause corrosion problems in the polymerization reactor. Since a higher proportion of the aqueous / organic phase is required to be able to dissolve the salt, large amounts of salt also reduce the amount of microspheres produced per batch.

An object of the present invention is to provide an expandable microsphere with a high expansion temperature.

Another object of the present invention is to provide expandable microspheres having a wide range of expansion.

Another object of the present invention is to provide expanded microspheres having excellent volume retention at high temperatures.

Surprisingly, it has been found that polymer shells can fulfill one or more of these objectives by providing expandable microspheres, which are copolymers of methacrylamide and methacrylonitrile as main components.

One aspect of the present invention relates to a thermally expandable thermoplastic microsphere comprising a polymer shell made from an ethylenically unsaturated monomer encapsulated with a propellant, wherein the ethylenically unsaturated monomer is from 21 to 80% by weight of methacrylamide and meta. 20% to 70% by weight of acrylonitrile, and the total amount of methacrylamide and methacrylonitrile is 70% to 100% by weight of the ethylenically unsaturated monomer.

Another aspect of the present invention relates to a method for producing a thermally expandable microsphere, comprising polymerizing an ethylenically unsaturated monomer in the presence of a propellant to obtain a microsphere comprising a polymer shell encapsulated by the propellant. , The ethylenically unsaturated monomer comprises 21% to 80% by weight of methacrylamide and 20% to 70% by weight of methacrylonitrile, and the total amount of methacrylamide and methacrylonitrile is 70% of the ethylenically unsaturated monomer. Weight percent to 100 weight percent.

Another aspect of the invention relates to expanded microspheres obtained by expanding the expandable microspheres of the invention.

A further aspect of the invention relates to the use of the thermally expandable microspheres of the invention as blowing agents.

A further aspect of the invention relates to expandable formulations comprising a thermoplastic polymer matrix and the expandable microspheres of the invention, and to the manufacture of such formulations.

These and other aspects will be described in more detail below.

The ethylenically unsaturated monomer preferably contains 30% to 80% by weight of methacrylamide, 31% to 80% by weight, 30% to 70% by weight, or 40% to 60% by weight. Moreover, the ethylenically unsaturated monomer preferably contains 30% to 65% by weight, 30% to 60% by weight, or 40% to 60% by weight of methacrylonitrile.

The total amount of methacrylamide and methacrylonitrile may be 80 wt% to 100 wt%, 90 wt% to 95 wt%, and 100 wt% or less of the ethylenically unsaturated monomer.

The weight ratio of methacrylonitrile: methacrylamide is preferably 2.5: 1 to 1: 2.5, especially 1.8: 1 to 1: 1.8, or 1.5: 1 to 1: 1.5.

The ethylenically unsaturated monomers include divinyl benzene, ethylene glycol di (meth) acrylate, di (ethylene glycol) di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, Neopentyl glycol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa ( Meth) acrylate, triallyl formal tri (meth) acrylate, allyl methacrylate, trimethylol propane tri (meth) acrylate, tributanediol di (meth) acrylate, PEG # 200 di (meth) acrylic Rate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, 3-acryloyloxyglycol monoacrylate, triacrylic formal, triallyl isocyanate, triallyl isocyanurate, etc. As with one or more, one or more crosslinking monomers having two or more polymerizable carbon-carbon double bonds may be further included. Particularly preferred is at least a trifunctional crosslinking monomer, examples of which are pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, triallyl formal tri (Meth) acrylate, trimethylol propane tri (meth) acrylate, triacrylic formal, triallyl isocyanate, and triallyl isocyanurate.

The amount of the crosslinking functional monomer may be, for example, 0.01% to 3%, 0.1% to 1%, or 0.2% to 0.5% by weight of the ethylenically unsaturated monomer.

The ethylenically unsaturated monomer may or may not include a carboxylic acid monomer, or may contain less than 10% by weight of a carboxylic acid monomer, for example, a carboxylic acid monomer including a monomer such as methacrylic acid or acrylic acid. It may include less than 5% by weight or less than 2% by weight.

When an ethylenically unsaturated monomer having only one carbon-carbon double bond other than methacrylonitrile and methacrylamide is included, the amount thereof is preferably 0% by weight to 10% by weight, most preferably 0% by weight to 5% by weight %, Or 0% to 2% by weight. Examples of these other types of monomers that may be included include nitrile-containing monomers such as acrylonitrile, α-ethoxyacrylonitrile, fumaronitrile or crotonitrile; Vinyl pyridine; Vinyl esters such as vinyl acetate; Styrenes such as styrene, halogenated styrene or α-methyl styrene; Dienes such as butadiene, isoprene and chloroprene; Unsaturated carboxyl compounds such as acrylic acid, methacrylic acid and salts thereof; Unsaturated esters such as methyl acrylate or methyl methacrylate or ethyl acrylate or ethyl methacrylate; Unsaturated halogenated compounds such as vinyl chloride, vinylidene fluoride and vinylidene chloride, or other unsaturated monomers such as acrylamide, or N-substituted maleimide.

In one embodiment, the ethylenically unsaturated monomer consists essentially of or consists of methacrylonitrile and methacrylamide, and one or more crosslinking monomers having two or more carbon-carbon double bonds.

The softening point of the polymer shell, which usually corresponds to its glass transition temperature (T _g ), is preferably in the range of 50 ° C to 250 ° C, or 100 ° C to 230 ° C.

Preferably, the polymer shell comprises 50% to 95% or 60% to 90% by weight of the total microspheres.

The propellant is usually a liquid whose boiling point is not higher than the softening point of the thermoplastic polymer shell, n-pentane, isopentane, neopentane, cyclopentane, cyclohexane, n-butane, isobutane, n-hexane, isohexane, neohexane, hydrocarbons such as n-heptane, iso-heptane, n-octane, isooctane, isodecan, isododecane or mixtures thereof. In addition to this, petroleum or fluorinated hydrocarbons such as petroleum ether, or methyl chloride, methylene chloride, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, trichlorofluoromethane, perfluorinated hydrocarbon, etc. Other hydrocarbon types such as can also be used. Particularly preferred propellants include one or more of isobutane, isopentane, isohexane, cyclohexane, isooctane, isododecane and mixtures thereof, preferably isooctane.

The boiling point of the propellant at atmospheric pressure may preferably be in a wide range of -20 ° C to 200 ° C, most preferably -20 ° C to 150 ° C. The boiling point or boiling range temperature of the propellant is above 50 ° C, more preferably above 60 ° C, most preferably above 70 ° C, preferably below 150 ° C, so that at least 50% by weight of the propellant at atmospheric pressure, preferably 80% by weight It is particularly preferred to allow more than% to evaporate.

In one embodiment, the propellant preferably comprises isooctane in an amount of at least 25% by weight, at least 50% by weight, preferably at least 60% by weight or at least 70% by weight, or possibly even substantially substantially It is composed of. The propellant may further include one or more of butane, pentane, hexane, heptane, petroleum distillate, isododecane, or other liquids that provide an appropriate boiling range of the propellant. Particularly preferred hydrocarbons for use in combination with isooctane are one or more of isobutane, isopentane, isohexane, n-pentane, n-hexane, petroleum ether, isododecane and n-heptane. For example, isooctane can be used with isopentane, isododecane, or mixtures thereof.

The propellant comprises, for example, 5% to 50%, or 10% to 40% by weight of the total weight of the microspheres.

Apart from the polymer shell and propellant, the microspheres may further include a component added during its preparation, usually 1 to 20% by weight, preferably 2 to 10% by weight. Examples of such components include solid suspending agents, such as one or more silica, chalk, bentonite, colloidal clay, boron nitride, starch, gum agar, modified polysaccharides such as methyl cellulose, Hydroxypropyl methylcellulose, carboxy methylcellulose, starch ether, starch ester, crosslinked polymers, polymer particles such as polyamide, polycarbonate, polyether, polyethylene, polypropylene, polystyrene, polyacrylate, and / or Or one or more salts of metals such as Al, Ca, Mg, Ba, Fe, Zn, Ni and Mn, Ti, oxides or hydroxides such as calcium phosphate, calcium carbonate, magnesium hydroxide, barium Sulfate, calcium oxalate, titanium dioxide, and hydroxides of aluminum, iron, zinc, nickel, or manganese. When these solid suspending agents are present, they are usually located mainly on the outer surface of the polymer shell. However, even if a suspending agent is added during the preparation of the microspheres, it can be washed off and removed in a later step and thus may not be substantially present in the final product.

Preferably, the microspheres of the composition have a relatively high T _start and T _max . T _start is preferably 130 ° C to 230 ° C, most preferably 150 ° C, or 180 ° C to 200 ° C. T _max is preferably 170 ° C to 270 ° C, and most preferably 200 ° C to 260 ° C.

The expandable microspheres are preferably 1 μm to 500 μm, more preferably 5 μm to 100 μm, most preferably 10 μm to 70, as measured by laser light scattering on a Malvern Mastersizer Hydro 2000 SM instrument on a wet sample. It has a volume median diameter of μm.

A further aspect of the invention relates to a method of making an expandable thermoplastic microsphere as described above. The method comprises polymerizing the aforementioned ethylenically unsaturated monomer in an aqueous suspension, preferably in the presence of a propellant, to obtain a microsphere comprising a polymer shell encapsulated by the propellant. With regard to the types and amounts of monomers and propellants, reference is made to the above description of expandable microspheres. Manufacturing can follow the same principles as described in the patent publication already mentioned.

In one embodiment of the invention, the microspheres are prepared in a batchwise process, and then polymerization can be performed in a reaction vessel as described below. For 100 parts of the monomer phase (suitably comprising monomers and propellants, the proportion of monomers in the polymer shell and the proportion determining the amount of propellant in the final product), one or more polymerization initiators, for example 0.1 parts To 5 parts, aqueous phase, for example 100 parts to 800 parts, and one or more preferably solid colloid suspending agents, for example 1 part to 20 parts, are mixed and homogenized. The size of the droplets on the monomers obtained determines the size of the final expandable microspheres according to the principles described in US Pat. No. 3615972, which can be applied to all similar manufacturing methods using various suspending agents, for example. The temperature is suitably maintained at 40 ° C to 90 ° C, preferably 50 ° C to 80 ° C, while the appropriate pH is dependent on the suspending agent used. For example, a high pH, preferably pH 5 to 12, most preferably pH 6 to 10, is a salt, oxide, or hydroxyl of a metal such that the suspending agent is Ca, Mg, Ba, Zn, Ni and Mn. Suitable when selected from one or more of side, such as zinc, nickel, or manganese calcium phosphate, calcium carbonate, magnesium hydroxide, magnesium oxide, barium sulfate, calcium oxalate, and hydroxide . Low pH, preferably pH 1 to 6, most preferably pH 3 to 5, the suspending agent is starch, methyl cellulose, hydroxypropyl methylcellulose, hydroxypropyl methylcellulose, carboxy methylcellulose, gum agar, silica, Colloidal clay, or an oxide or hydroxide of aluminum or iron, is suitable. Each one of the above formulations has a different optimal pH, for example, depending on the solubility data.

To enhance the effect of the suspending agent, it is also possible to add one or more accelerators in small amounts, for example from 0.001% to 1% by weight. Typically, these accelerators are organic substances, for example, water-soluble sulfonated polystyrene, alginate, carboxymethylcellulose, tetramethyl ammonium hydroxide or chloride or water-soluble complex resinous amine condensation products such as diethanolamine and adiph Water-soluble condensation products of acids, ethylene oxide, water-soluble condensation products of urea and formaldehyde, polyereneimines, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylamine, amphoteric substances, such as proteinaceous Non-ionic substances such as methoxycellulose, soaps, alkyl sulfates and sulfonates, and long chain quaternary ammonium compounds, ionic substances classified as emulsifiers, such as, gelatin, glue, casein, albumin, glutin, etc. It may be selected from one or more of.

Conventional radical polymerization can be used, and the initiator is suitably selected from one or more of organic peroxides such as dialkyl peroxides, diacyl peroxides, peroxy esters, peroxy dicarbonates, or azo compounds. do. Suitable initiators include dicetyl peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate, dioctanoyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, di Decanoyl peroxide, tert-butyl peracetate, tert-butyl perlaurate, tert-butyl perbenzoate, tert-butyl hydroperoxide, cumene hydroperoxide, cumene ethyl peroxide, diisopropylhydroxy dicarboxyl Rate, 2,2'-azobis (2,4-dimethyl valeronitrile), 2,2'-azobis (isobutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile ), Dimethyl 2,2'-azobis (2-methylpropionate), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide] and the like. It is also possible to initiate polymerization using radiation such as high energy ionizing radiation.

When polymerization is essentially complete, microspheres are usually obtained as aqueous slurries or dispersions, which can be used by themselves, or bed filtering, filter pressing, leaf filtering, Dehydrated by any conventional means such as rotary filtering, belt filtering or centrifugation, so-called wet cakes can be obtained. However, the microspheres are spray dried, shelf drying, tunnel drying, rotary drying, drum drying, pneumatic drying, and turbo shelf. Drying may be by any conventional means, such as turbo shelf drying, disc drying, or fluidized bed-drying.

Where appropriate, microspheres can be treated at any stage to reduce the amount of unreacted monomer remaining by any of the procedures described in WO 2004/072160 or US 4287308 mentioned previously, for example.

The microspheres of the present invention are useful in a variety of applications, such as injection molding or extrusion molding, as blowing agents for thermoplastics, especially high melt thermoplastics.

One aspect of the present invention relates to an expanded microsphere obtained by expanding an expandable microsphere as described above, for example, to a particle diameter of 2 to 5 times larger than the diameter of an unexpanded microsphere. Expansion is effected by heating the expandable microspheres to a temperature above T _start . The upper temperature limit is set until the microspheres begin to decay, depending on the exact composition of the polymer shell and propellant. In most cases, temperatures between 100 ° C and 250 ° C are suitable. The density of the expanded microspheres can be controlled by selecting the heating temperature and heating time. The expansion can be effected with any suitable heating means in any suitable equipment, for example as described in EP 0348372, WO 2004/056549, or WO 2006/009643.

Certain aspects of the invention relate to the use of expandable microspheres as described above in expandable formulations comprising a thermoplastic polymer matrix and expandable microspheres. The formulation optionally further comprises one or more additives such as colorants, stabilizers, adjuvants, and the like. Examples of expandable formulations include moldable composite sheets and compounds for use in injection molding, extrusion, blow molding, rotational molding, thermoforming, and the like. The amount of expandable microspheres is preferably 0.5% to 15% by weight or 1% to 5% by weight. The polymer matrix is, for example, polypropylene, polystyrene, polyethylene, thermoplastic polyurethane, polyamide, polycarbonate, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer, styrene-ethylene-butylene -Styrene copolymers, styrene-butadiene-styrene copolymers, polyvinyl chloride, ethylene-vinyl acetate copolymers or copolymers thereof, or another polymer having a similar melting point.

The invention also relates to an expandable formulation as described above comprising a thermoplastic polymer matrix and an expandable microsphere as described above and optional additional additives as described above.

Moreover, the present invention comprises the steps of mixing the thermoplastic polymer matrix and the expandable microspheres as described above and optional additional additives as described above at a temperature above the melting point of the polymer but below the expansion temperature (T _start ) of the microspheres. It relates to a manufacturing method, including.

Example

The invention will be further described in conjunction with the following examples, but it should not be construed as limiting the scope of the invention. Unless otherwise specified, all parts and percentages refer to parts by weight and% by weight.

The expandability of the microspheres was evaluated in Mettler Toledo TMA / SDTA 841 ^e using a heating rate of 20 ° C./min and a load of 0.06 N (net.). T _start is the temperature at which the expansion starts, T _max is the temperature to reach a maximum of expansion, D _min is the density of the microspheres in T _max, △ T _1/2 is the column height of the mechanical analysis curve (TMA curve) The width at half, the curve is a plot of probe displacement over temperature due to expansion of the microspheres. The larger the number of ΔT _1/2, the wider the expansion range. F ₃₀₀ is the ratio of the expansion at 300 ° C. divided by the maximum expansion, for example, when F ₃₀₀ is 50%, half of the maximum expansion volume is reached or maintained at 300 ° C. Heat resistance was further evaluated isothermally at 250 ° C. and 0.06 N rod (net.). Heating was performed to 230 ° C at a rate of 20 ° C / min, to 240 ° C at a rate of 10 ° C / min, and to 250 ° C at a rate of 5 ° C / min, after which the temperature was maintained at 250 ° C for 1 hour. Heat resistance is defined as the volume retention of expanded microspheres and is presented as the ratio of the expansion after 0, 15, 30, 45, and 60 minutes at 250 ° C. divided by the maximum expansion reached during the analysis.

Particle size and particle distribution were measured by laser light scattering on a Malvern Mastersizer Hydro 2000 SM instrument on a wet sample. The particle size is given by the volume median diameter D (0.5).

The amount of propellant was determined by thermal gravimetric analysis (TGA) in Mettler Toledo TGA / SDTA851 ^e . All samples are analyzed after drying to remove as much moisture as possible and, if any, residual monomer is also removed. The analysis was performed under nitrogen atmosphere at a heating rate of 20 ° C / min starting at 30 ° C. In some cases, it has been difficult to accurately measure the amount of propellant because it is difficult to discriminate between weight loss due to loss of propellant and weight loss due to degradation of the polymer.

Example  One

A reaction mixture comprising Mg (OH) ₂ -stabilized organic droplets in water was prepared by mixing the phases and vigorously stirring until proper droplet size was achieved. The water dispersion contained 4.9 parts of Mg (OH) ₂ and 370 parts of water. The organic droplet contained 2 parts of dilauroyl peroxide, 25 parts of isooctane, 50 parts of methacrylonitrile, 50 parts of methacrylamide, and 0.4 parts of trimethylolpropane trimethacrylate. The polymerization was carried out in a sealed reactor under agitation at 62 ° C for 11 hours, followed by 80 ° C for 4 hours. After cooling to room temperature, the sample of the obtained microsphere slurry was removed to measure the particle size distribution. After filtration, washing and drying, the particles were analyzed by TMA. The dry particles contained about 31% by weight of isooctane, and the median particle size was about 51 μm. The TMA-results are confirmed in Table 1.

Example  2 to 11

Microspheres were prepared in a plurality of polymerization experiments performed in Example 1, but monofunctional monomers (i.e., those having only one carbon-carbon double bond) were added according to Table 1. The polymerization was carried out as in Example 1, but in the case of Example 2, the polymerization was performed at 62 ° C for 20 hours. Table 1 shows the results of the analysis.

Analysis results for Examples 1 to 11, and the amount of charged monomer. Example
M1 ^a
(Part (p rates )) M2 ^b
(part) size
(㎛) Propellant
(weight%) T _start (℃) T _max (℃) D _min  (g / l) △ _1/2 (℃) F ₃₀₀  (%) One 50 50 51 31 201 284 11.6 102 96 2 50 50 64 23 Do not swell 3 50 50 38 13 Poor expansion 4 50 50 17 33 Poor expansion 5 50 50 19 9 Do not swell 6 50 50 11 13 Do not swell 7 80 20 28 8 Do not swell 8 70 30 48 16 130 222 60.6 25 13 9 60 40 52 20 188 225 12.8 129 73 10 40 60 60 28 213 293 27.1 90 99 11 30 70 57 31 226 315 149 83 97

a) M1 is methacrylonitrile (MAN) in Examples 1 and 3 to 11, acrylonitrile (AN) in Example 2, and b) M2 is methacrylamide in Examples 1, 2 and 7 to 11. and (MAAM), and acrylamide in example 3, N in examples 4 - (hydroxymethyl) - and acryl amide, N, N in example 5-a-dimethyl acrylamide, N in examples 6 - ( 3- (dimethylamino) propyl) -methacrylamide.

In Table 1, it can be achieved when a thermally expandable microsphere having a high T _start , a wide expansion range, and an excellent volume retention at 300 ° C. is used as methacrylonitrile and methacrylamide as a monofunctional monomer. It can be seen that the microspheres of Comparative Examples 2 to 7 do not expand or expand poorly.

Example  12 to 16

Microspheres were prepared in a plurality of polymerization experiments performed in Example 1, but propellants were added according to Table 2. Table 2 shows the results of the analysis.

Analysis results for Examples 12-16 using different propellants. Example
Propellant ^a mixture ^b
(part) size
(㎛) Propellant
(weight%) T _start (℃) T _max (℃) D _min  (g / l) △ _1/2 (℃) F ₃₀₀  (%) 12 IP 100 49 22 195 251 58.9 108 89 13 IP / IO 50/50 63 25 189 252 28.5 119 91 14 IO / ID 75/25 56 29 204 250 13.2 89 62 15 IO / ID 50/50 53 31 216 253 12.7 91 68 16 ID 100 60 31 218 237 53.0 59 47

a) The different propellants used are isopentane (IP), isooctane (IO), and isododecane (ID). b) The total weight of the propellant used in the experiment is the same.

In Table 2, it can be seen that thermal expansion expandable microspheres with high T _start , wide expansion range, and excellent volume retention at 300 ° C. were achieved when various hydrocarbon compounds were used as propellants.

Example  17 to 28

Microspheres were prepared in a plurality of polymerization experiments performed in Example 1, but the monofunctional monomer was added according to Table 3. In addition, in Example 21, 0.5 part of trimethylolpropane trimethacrylate was used. The polymerization was carried out as in Example 1, but in the case of Example 21, the polymerization was performed at 62 ° C for 20 hours. Table 3 shows the results of the analysis.

Analysis results for Examples 17-28 including MAN / MAAM in combination with other monomers (X). room Poem
X ^a MAN / MAAM / X
(part) size
(㎛) Propellant
(weight%) T _start (℃) T _max (℃) D _min  (g / l) △ _1/2 (℃) F ₃₀₀  (%) 17 AN 49/49/2 60 28 185 261 10.6 82 56 18 AN 48/48/4 61 25 196 253 8.2 61 12 19 AN 47/47/6 58 29 193 239 7.4 44 4 20 AN 45/45/10 56 20 184 217 13.1 26 0 21 AN 26/25/49 48 24 164 185 124 25 Na ^b 22 MA 49/49/2 54 29 197 244 13.3 87 51 23 MA 47.5 / 47.5 / 5 58 29 200 241 11.4 49 13 24 MA 45/45/10 57 28 189 221 25.0 23 0 25 MMA 47.5 / 47.5 / 5 65 31 201 258 10.2 93 71 26 VDC 49/49/2 57 29 202 243 12.4 97 72 27 VDC 47.5 / 47.5 / 5 49 31 198 243 13.4 65 32 28 VDC 45/45/10 34 32 199 242 33.0 50 27

a) AN = acrylonitrile, MA = methyl acrylate, MMA = methyl methacrylate, VDC = vinylidene chloride. b) If not analyzed, the sample has already lost its swelling at 220 ° C.

In Table 3, it can be seen that the broad expansion range and excellent volume retention at 300 ° C. in microspheres having copolymer shells from methacrylonitrile and methacrylamide are adversely affected by the addition of other monofunctional monomers.

Example  29 ( EP  1577359)

Microspheres were prepared as in Example 1, but in the case of monomers and propellants, organic droplets were stabilized by using a silica water dispersion instead of Mg (OH) ₂ . Organic droplets are 0.8 parts of dilauroyl peroxide, 13 parts of isohexane, 13 parts of isooctane, 40 parts of acrylonitrile, 23 parts of methacrylonitrile, 30 parts of methacrylic acid, 3.5 parts of methacrylamide, 3.5 parts of styrene and die It consisted of 0.2 parts of ethylene glycol dimethacrylate. The water dispersion is 244 parts of water, 10 parts of 1 M NaOH, 17 parts of 10% acetic acid, 0.3 parts of Cr (NO ₃ ) ₃ , 10 parts of 40% colloidal silica, 0.9 parts of condensation product of diethanolamine and adipic acid, ascorbic acid 1.5 parts and Na ₂ SO ₄ It was prepared by mixing 7 parts. Polymerization was carried out at 70 ° C for 20 hours. The analysis results can be found in Table 4.

Example  30 ( EP  1964903)

Microspheres were prepared as in Example 29, but the organic droplets consisted of 54 parts of methacrylonitrile, 46 parts of methacrylic acid, 30 parts of isooctane and 2.4 parts of dilauroyl peroxide. Polymerization was carried out at 60 ° C for 15 hours, followed by 70 ° C for 9 hours. The analysis results can be found in Table 4.

Example  31 ( EP  1964903)

Microspheres were prepared as in Example 30, but the monomer consisted of 64 parts of methacrylonitrile and 36 parts of methacrylic acid. The analysis results can be found in Table 4.

Analysis results for Examples 29-31. Example size
(㎛) Propellant
(weight%) T _start (℃) T _max (℃) D _min  (g / l) △ _1/2 (℃) F ₃₀₀  (%) 29 5.6 34 192 202 10.8 28 0 30 9.5 25 220 263 31.1 88 67 31 9.4 26 219 236 11.9 49 11

Heat resistance

In Table 5, the microspheres according to the invention (Examples 1 and 9) with copolymer shells derived from methacrylonitrile and methacrylamide are 250 ° C. compared to Examples according to the prior art (Examples 29 to 31). It can be seen that it has an excellent volume retention rate even after being heated for 1 hour.

Volume retention of microspheres after heating at 250 ° C. Example 0 min (%) 15 min (%) 30 min (%) 45 min (%) 60 min (%) One 100 99 97 94 91 9 90 89 89 87 84 29 20 14 7 4 3 30 91 68 63 59 56 31 77 48 41 37 33

Claims (16)

A thermally expandable thermoplastic microsphere comprising a polymer shell made from an ethylenically unsaturated monomer encapsulated with a propellant,
The ethylenically unsaturated monomer
Methacrylamide 21% to 80% by weight,
20 to 70% by weight of methacrylonitrile, and
5% by weight or less of another ethylenically unsaturated monomer having only one carbon-carbon double bond
Including,
The total amount of the methacrylamide and methacrylonitrile is 70 to 100% by weight of the ethylenically unsaturated monomer, thermally expandable thermoplastic microspheres. The thermally expandable thermoplastic microsphere according to claim 1, wherein the ethylenically unsaturated monomer comprises 30% to 70% by weight of methacrylamide and 30% to 60% by weight of methacrylonitrile. The thermally expandable thermoplastic microsphere according to claim 1, wherein the ethylenically unsaturated monomer comprises methacrylamide at 31% to 80% by weight. The thermally expandable thermoplastic microsphere according to claim 2, wherein the ethylenically unsaturated monomer comprises methacrylamide at 40% to 60% by weight. According to claim 2, The ethylenically unsaturated monomer is characterized in that it comprises 40 to 60% by weight of methacrylonitrile, thermally expandable thermoplastic microspheres. The thermally expandable thermoplastic microsphere according to any one of claims 1 to 5, wherein the total amount of the methacrylamide and the methacrylonitrile is 80% to 100% by weight of the ethylenically unsaturated monomer. The thermally expandable thermoplastic microsphere according to any one of claims 1 to 5, wherein the total amount of the methacrylamide and the methacrylonitrile is 90% to 100% by weight of the ethylenically unsaturated monomer. The thermally expandable thermoplastic microsphere according to any one of claims 1 to 5, wherein the ethylenically unsaturated monomer contains no carboxylic acid-containing monomer or contains less than 10% by weight. The thermally expandable thermoplastic microparticle according to any one of claims 1 to 5, wherein the propellant comprises a hydrocarbon selected from isobutane, isopentane, isohexane, cyclohexane, isooctane, isododecane and mixtures thereof. sphere. The thermally expandable thermoplastic microsphere according to claim 9, wherein the propellant comprises 50 to 100% by weight of isooctane. Polymerizing an ethylenically unsaturated monomer in the presence of a propellant to obtain a microsphere comprising a polymer shell encapsulated by the propellant
A method for producing a thermally expandable microsphere according to any one of claims 1 to 5, comprising: An expanded microsphere obtained by expanding the expandable microsphere according to any one of claims 1 to 5. An expandable formulation comprising a thermoplastic polymer matrix and the expandable microspheres according to claim 1. The thermally expandable thermoplastic microspheres according to any one of claims 1 to 5, wherein the thermally expandable thermoplastic microspheres are used as a blowing agent in an injection molding or extrusion molding process. The expandable formulation of claim 13, wherein the expandable formulation is used as a blowing agent in an injection molding or extrusion molding process. delete